It is desirable for many purposes to be able to measure accurately a magnetic field. Magnetometers can be used as compasses and are useful in many areas, including virtual reality equipment, electronic games, and automotive products.
Conventional methods to sense magnetic fields include devices that measure the Hall effect, flux change, magnetoresistance, or giant magnetoresistance. While such methods can be effective, there are many areas in which these conventional devices could be improved. For example, it would be advantageous to improve the temperature coefficient and the stability of offsets in such devices, to obtain extremely high sensitivity with high dynamic range, to obtain true tilt sensing instead of total field sensing, to obtain higher linearity, to provide on-chip signal processing with an analog or digital output, to be able to measure magnetic fields in multiple axes with a single device, and to reduce the size of such devices. Also, it would be advantageous to be able to integrate a magnetometer with micromachined inertial sensors, such as accelerometers or yaw rate sensors, on a single chip.